Vapor generator



March 26, 1963 A. vlscHER, JR 3,083,288

VAPOR GENERATOR 5 Sheets-Sheet 1 Filed Nov. 27. 1959 A Trae/VE Ys.

March 26, 1963 A. viser-1ER, JR

VAPOR GENERATOR 5 Sheets-Sheet 2 Filed Nov. 27, 1959 March 26, 1963 A. vlscHER, JR 3,083,288

VAPOR GENERATOR Filed Nov. 27, 1959 5 Sheets-Sheet I5 Arma/evs March 26, 1963 A. vlscHER, JR 3,083,288

VAPOR GENERATOR Filed Nov. 2'7, 1959 5 Sheets-Sheet 4 i@ E CL :a l L 'u N 03; LOE Q 2 a 2 a: Si( k E S e E il rm... ,ma

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March 26, 1963 A. v1scHER,JR 3,083,288

VAPOR GENERATOR Filed Nov. 27, 1959 5 Sheets-Sheet 5 INVENTOR. ALF-250 Msc/Jee, Je. BY

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United States Patent O 3,083,238 VAPOR GENERATOR Alfred Vischer, Jr., Park Ridge, Ill., assigner of small interests to various assignees Filed Nov. 27, 1959, Ser. No. 355,764 1l) Claims. (Cl. 219-40) The present invention relates to vapor generators and it particularly' relates to vapor generators of the type in which a plurality of electrodes are positioned in direct Contact with an electrically conductive liquid to be vaporized so that a voltage source may be connected between the electrodes to cause an electric current to pass through the liquid to heat and vaporize it.

A principal object of thc present invention is to provide a new and improved vapor generator of the above described type which is small and compact in design and can generate relatively large quantities of vapor in short periods of time.

Another' object of the present invention is to provide a new and improved vapor generator of the above dcscribed type in which there are no moving parts located within the vaporizing chamber.

A further object of the present invention is to provide a new and improved vapor generator which is simple in construction, reliable in use, inexpensive to manufacture, and small in size in relation to the quantity of steam which it can generate.

Another object of the present invention is to provide a new and improved vapor generator which is self-regulated so as to provide a constant output pressure.

Briefly, the above and further objects are realized in accordance with one aspect of the present invention by providing an electrolytic type steam generator in which the supply of water to the vaporizing chamber is controlled in response to the current llowing in the Vaporizing electrode circuits as well as in response to the output vapor pressure of the generator. Accordingly, all moving parts within the generator are eliminated. In addition, the size of the vaporizing chamber is minimized by the use of an electrode design in which a plurality of fingers on respective ones of a pair of electrodes are interleaved to provide a large electrode surface area within a minimum of space.

The invention, both as `to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following detailed description taken in connection with the accompanying drawings, in which:

FIG, l is a top view of a vapor generator embodying certain features ofthe present invention;

FIG. 2 is a vertical sectional view of the vapor generator shown in FIG. 1, talzen along the line 2 2 thereof;

FIG. 3 is a sectional view `talen along the line 3 3 of FG. 2 assuming the entire generator to be shown therein;

FIG. 4 is a sectional view taken along the line 4 4 of FIG. 2 assuming the entire generator to be shown therein;

FIG. 5 is a fragmentary sectional View taken along the line 5 5 of FIG. 3;

iG. 6 is a fragmentary sectional view taken along the line 6 6 of FIG. 4;

FIG. 7 is a fragmentary sectional view taken along the line 7 7 of FIG. 2;

FIG. 8 is a schematic circuit diagram of a steam generator control system embodying the present invention;

FIG. 9 is a schematic circuit diagram of another steam generator control system embodying the present invention;

FIG. 10 is a sectional view of a pressure regulator ern- 3,683,288 Patented Mar. 26, 1953 TCC ployed in the illustrated embodiment of the present invention;

FIG. 11 is an elevational view, partly schematic, of a vapor generator embodying the present invention; and

FIG. 12 is an elevational view, partly in section, of another vapor separator embodying the present invention.

Referring now to the drawings and particularly to FIGS. 1 7 thereof, the present invention is shown as embodied in a steam generator 10 which comprises a tubular chamber defining member or housing 11 in which a pair of vaporizing electrodes 12 and 13 are spatially mounted. A source of voltage is adapted to be connected between the electrodes 12 and 13, and the liquid to be vaporized, which ordinarily is water, may be supplied to the Vaporizing chamber through a combined inlet and outlet passageway 14 provided in the bottom of the housing 11. Electric areing between the electrodes 12 and 13 and the housing il., which is ordinarily connected to electrical ground, is prevented by means of an insulating lining l5 which is preferably molded of Tellen, `and seats against the inner wall of the chamber 11.

In order to prevent dirt or other residue from collecting in the bottom of the vaporizing chamber and possibly short-circuiting the electrodes 12 and 13, the electrodes l2 and 13 depend from the top of the chamber and terminate a substantial distance above the bottom thereof. Moreover, the bottom of the vaporizing chamber is generally conical, sloping down into the central passageway 14 so that any particles which may collect at the bottom of the vaporizing chamber naturally tend to move under the force of gravity through the passageway `14. As more fully described hereinafter, water frequently flows out of the generating chamber through the passageway 14 and, therefore, the flow of water across the bottom of the chamber also `serves to remove any foreign particles lying on the bottom thereof.

Referring particularly to FlG. 3, there is provided in accordance with the present invention an electrode conguration which provides a large electrode surface area in relation to the overall size of the electrodes, thereby to enable the generation of substantial quantities of steam with a generator of relatively small size. As shown, each of the electrodes 12 and 13 is provided with a plurality of interleaved finger-like projections, generally designated 12a and 13a, respectively. Preferably, the electrodes 12 and 13 are manufactured by mounting a cylindrical piece of carbon in a jig, and then sawing the carbon piece into two parts by removing the tortuous area which is generally designated 17 in FIG. 3.

Referring particularly to FIGS. 2, 4 and 7, the mounting assembly for the electrodes 12 and 13 comprises an insulating disc 2l) which is secured to a top insulator or cover 22 by means of a pair of conductive studs 21, the insulating disc 20 in turn being fixedly connected to the electrodes 12 and 13. Considered in greater detail, the electrodes 12 and 13 are each provided with peripheral V-grooves 12b and 13b in the respective upper ends thereof, and as best shown in FIG. 6, an annular V-shaped tongue 24 on the insulating disc 20 lits into the grooves 12b and 13b to accurately position the electrodes 12 and 13 with respect to one another and with respect to the insulating disc 20. In order to attach the electrodes 12 and i3 to the disc 29, four semicircular counterbores 25, and an associated trunnion 26, one set of which is shown in FIG. 5, are provided in the side of the disc 20, and the electrodes l2 and 13 are each respectively provided with two semicircular counterbores 12C and 13e and associated trunnions `12d and 13d which respectively mate with the counterbores 25 to form circular counterbores in the disc and electrode assembly when the electrodes 12 and 13 are properly assembled to the disc 20. Therefore, with the electrodes 12 and 13 and the disc 20 so assembled, four aoeaase split, resilient snap rings 27, which are normally biased closed, are opened and snapped into the circular counterbores over the composite studs thereby to clamp the electrcdes 12 and 13 to the insulating disc 20.

Referring again to FIG. 2, the studs 21 are electrically connected to the electrodes 12 and 13 by a pair of flexible, stranded cable conductors 28 and thus provide the electric terminal studs for the generator 10. They each have a square bottom portion 29 which seats in the inner end of respective ones of correspondingly shaped radial slots in the insulating disc 20, and the studs 21 are respectively secured to the disc 20 by means of bridge pieces 31, each of which, as best shown in FIG. 4, is secured to the disc 20 by a pair of machine screws 32 and 33. Each of the bridges 31 includes a slot 34 in which a reduced area portion 35 of the stud 21 is received. As shown best in FIGS. 2 and 7, the height of the reduced area portion 35 is substantially greater than that of the bridge 31, and in order to prevent spurious movement of the electrode assembly within the vaporizing chamber 11, a pair of coil springs 37 are loosely mounted in a pair of circular recesses 38 provided in the top of the disc 20. In the final assembly the springs 37 are slightly compressed between the disc 20 and the cover 22 so as to exert a downward force on the disc 20 to urge the bridge 31 against the bottom shoulder 35a of the reduced portion 35. This prevents movement of the assembled parts while retaining some resiliency against shock.

Each terminal stud 21 further includes a square intermediate portion 36 which is received in a counterbore 39 in the cover 22, the counterbore 39 having a square outer portion and a circular bottom portion in which a circular portion 40 of the stud 21 is received. A suitable gasket 41 is positioned in the bottom of the hole 39 to seal the inner chamber from the atmosphere. As shown, the terminal stud 21 includes a threaded end portion 42 onto which a nut 43 is threaded to rigidly secure the terminal stud 21 to the cover 22, and the nut 43 includes a cylindrical portion 43a which seats in a counterbore 44 over a gasket 45.

In order to seal the cover 22 to the housing 11, the upper end 11a of the housing is flared outwardly and a gasket 46 is interposed between the end 11a and a generally tapered annular flange 22a on the cover 22. The cover 22 thus seats on the dlared end of the housing and an annular split clamp 48 which includes an annular channel member 49, is pressed over the assembly of the flared ends of the member 1l, the gasket 46 and the flange 22a to compress them together and thereby to sealably connect the cover 22 to the chamber defining member l1. A steam outlet fitting 51 is connected to the cover 22 and extends through a suitable central passageway therein to convey steam from the generator to the load.

Referring now to FIG. 8, there is shown a schematic circuit diagram of a control circuit embodying the present invention. This circuit controllably energizes the steam generator from an A.C. power source to which a pair of terminals 60 and 61 are adapted to be connected. As shown, a ganged on-oif switch 62 is provided for connecting the respective terminals 60 and 61 to the vaporizing electrodes 12 and 13. If there is a suticient amount of water in the chamber 11 to bridge the electrodes 12 and 13 when the switch 62 is closed, current flows through the water, thereby heating and vaporizing it so that steam passes to the load through the outlet 51 at the top of the generator `10.

In order to control the supply of water to the chamber 11, the inlet of a pressure regulator 64 is connected to a source of water (not shown), the regulator 64 having a controlled output pressure exceeding the desired output pressure of the generator by a small amount, and the water outlet of the regulator 64 is connected through a normally closed solenoid operated inlet valve 65 to the passageway 14 which connects to the bottom of the vaporizing chamber. The regulator 64 is of the type having a variable central orifice in the passageway therethrough for regulating the flow of water in accord with the difference in pressure between the outlet side of the regulator and the adjusted value thereof. For example, where the pressure regulator is set for 17 p.s.i. and the pressure at the outlet side is 17 p.s.i., the central orifice is closed, while if the outlet pressure is substantially less than 17 p.s.i., the central orifice is fully open. A pressure regulator of this type is shown in FIG. 10 and described hereinafter.

As shown in FIG. 8, the coil of a water feed control relay 66 is serially connected between the terminal 61 and the electrode 13, and a set of normally closed contacts 67 on this relay are serially connected with the control solenoid 68 of the inlet valve 65 and a set of normally closed contacts 69 on a pressure operated switch 70. The switch 70 is connected in the outlet steam line and is adjusted to open the contacts 69 when the pressure `at the output side of the generator 10 exceeds the desired output pressure of the generator 10. If the generator 10 is used in a pressure cooking system, this pressure will usually be about fteen pounds per square inch. The relay 66 is adjusted to operate when the current llowing between the electrodes 12 and 13 is above a predetermined value, which value occurs when the water in the vtaporizing chamber is at the highest level desired. Therefore, the relay 66 controls the level of the water in the vaporizing chamber and prevents it from overflowing. A solenoid operated drain valve 75 is connected between the passageway 14 and a suitable drain line, and the contnol solenoid 76 therefor is serially connected with the normally closed contacts 69 between the power terminals 60 land 61.

To consider the operation of the generator control system of FIG. 8 let it be assumed that the generator 10 has been deenergized and that it is desired to provide steam at a pressure of l5 p.s.i. Accordingly, the pressure switch 70 is adjusted to operate at a value of 15 p.s.i. and the water regulator 64 is adjusted to operate at a pressure slightly above this value, say 17 p.s.i. Of course, if it were desired to provide steam at a higher or lower pressure the switch 70 would be adjusted to operate at this other pressure and the operating pressure of the water regulator 64 would be adjusted to be somewhat above the value at which the switch 70 is set. In order to start the generator 10 the switch 62 is closed whereby the electrodes 12 and 13 are connected across a source of voltage and, since there is no water in the vaporizing chamber, the relay 66 is released and the solenoids 68 and 76 are both energized whereby the inlet valve 65 is opened and the outlet valve 75 is closed. Since there is no pressure in the vaporizing chamber, water ows through the regulator 64, the central orifice thereof is wide open land water flows into the vaporizing chamber where it bridges the electrodes 12 and 13. Current thus flows between the electrodes through the water land vaporizes some of it. Under most circumstances, water will flow into the charnber at a faster rate than it is vaporized so that the level of water in the chamber increases. When the water level becomes such that the current flowing between the electrodes 12 and 13 is above the predetermined value at which the relay 66 is adjusted to operate, the contacts 67 of the `relay 66 are opened thereby to deenergize the solenoid 68 to close the inlet valve 65. The supply of water to the generator is thus interrupted but since the electrodes 12 and 13 remain connected between the power terminals 60 and 61 steam continues to be generated. As a result, the water level begins to fall. As this occurs, the current flowing through the operating coil of the relay 66 decreases, and when it decreases to a value less than the drop-out current value for the relay, the contacts 67 again close to energize the solenoid 68 and open the inlet valve 65 which once more supplies water to the vaporizing chamber. Assuming that the pressure in the output line 51 now begins to increase as would normally 51 be the case, the back pressure on the water regulator 64 increases thereby causing the llow of water through the regulator 64 to diminish. If desired, the regulator 64 and the pressure switch 70 may be so adjusted that the regulator then passes only a sufiicient amount of water to replenish the amount of water required to develop the quantity of steam necessary to make up for the losses in the system. Preferably, the regulator 64 should supply a somewhat greater amount of water to the generator than is necessary for this purpose, and therefore, a steam pressure will be reached in the output line 51 which will cause the switch 70 to operate thereby to open the contacts 69 and to deenergize both the solenoid 68 and the solenoid 76. When this takes place, the inlet valve 65 closes rand the drain valve 75 opens thereby to drain water from the vaporizing chamber. As soon as water begins to drain from the chamber, however, the output pressure immediately decreases inasmuch as the steam in the system now occupies an additional volume. Accordingly, the switch 70 again operates to close the contacts 69. This closes the outlet valve 75 and opens the inlet valve 65 so that additional water is supplied to the vaporizing chamber, but the amount of water supplied at this time is, of course, substantially less than is supplied when the generator is first set into operation because of the action of the water regulator 64 which provides a reduced output ow of water as the pressure on the outlet side thereof increases.

Referring now to FIG. 9, in some instances where the water being used has a relatively high conductivity, it may be found that when the generator is first energized and water flows iat a high rate through the regulator 64 be cause of the fact that there is no substantial steam pressure within the vaporizing chamber, the level of water will overshoot the desired maximum value. This occurs because an excessive amount of water may liow into the vaporizing chamber before the inlet valve 65 can be closed. If the relay 66 were adjusted to operate at a lower current level so as to compensate for this effect by operating when the water level is below the maximum level which can be tolerated, then, during normal operation of the generator when only relatively small amounts of steam are generated, a lesser `amount of water would be contained in the vaporizing chamber `and in order to generate the same amount of steam, larger or additional electrodes would have to be used. Therefore, in accordance with another feature of the present invention the control circuit shown in FIG. 8 may be slightly modified to compensate for that condition Where the water has an excessive conductivity, by connecting the solenoid 76 of the drain valve '75 directly in parallel with the solenoid 68 of the inlet valve 65 as shown in FIG. 9. With this change in the circuit connections, the relay 66 operates not only to supply water to the generator but to open the drain valve 75 thereby to quickly drain ofi any excessive water which may ow into the generating chamber 11 as a result of an overshoot in the system. It will be understood, of course, that if this change in the circuit is made there will be considerably more water used by the generator since whenever the l5 pounds pressure is reached in the outlet line 51 and the contacts 69 are opened, not only is the supply of water to the generator interrupted but the drain valve is opened and some water necessarily drains out. However, where overshoot is a problem, the solenoids 68 and 76 `may be connected in parallel so that both of them are returned to the power terminal 61 through the normally closed relay contacts 67.

There is thus provided in accordance with the present invention a steam generator which is small in size and yet which will produce relatively large amounts of steam in a very short period of time and which, moreover, can accurately supply' small amounts of steam Such as are needed to compensate for losses in a system such as a pressure cool-1er.

Referring to FlG. l0, the regulator 64 is there shown as comprising a flexible diaphragm secured between a pair of upper and lower housing members 101 and 102. An inlet port 103 is connected to an outlet port 104 through an aperture 105 which is surrounded by a valve seat 106 toward which a valve disc 107 is movable in response to the pressure on the lower side of the diaphragm 100. The disc 107 is resiliently biased toward the seat 106 by means of a coil spring 108, and a coil spring 109 mounted in the upper portion of the housing acts through an actuating needle 111 to urge the disc 107 away from the seat 106. A thumb screw 112 which is threaded in the upper housing member 101 enables manual adjustment of the downward pressure on the needle 1.11 and the diaphragm 106 thereby to provide means for adjusting the output pressure from the regulator.

ln FiGS. 8 and 9, a single generator 10 has been illustrated as connected across a single phase AC. source, but if desired it could be energized from a D.C. source. However, where additional steam capacity is required, a number of generator units 10 may be multiplexed together using a single control system, only one generator being used for control purposes, the others being connected in parallel with the principal gcnerator and acting as slaves. Preferably, where two generators are used, the electrodes are connected to respective phases of a twophase power system, and where three generators are used the electrodes are connected to respective phases of a three-phase power system. ln this way, the power consumption of the generator is minimized.

Referring now to FIG. ll, there is shown a dual generator having twice the capacity of a single generator unit. When two generators 10 are operated together, only one set of control switches and relays are necessary, whereby the manufacturing cost per unit hours power of the generator is substantially less than that of a single generator. As shown, a commen water inlet and outlet connection is located between the two units and, moreover, centrally located so that equal water levels are maintained in the two vaporizing chambers.

lt has been found that where such equalization was not provided oscillation between the water levels in the two chambers occurred and appreciahly reduced the eilciency of operation of the generator. The steam output lines from the separate chambers are connected to a single outlet conduit at a point which is operatively midway between the two steam outlets and the pressure responsive switch 70 is operatively connected to this conduit down stream of the connection so as to be responsive to thc output pressure from both units.

Because of the high current drawn by each unit, it it preferable to energize the electrodos in each unit from a different phase of a multiple-phase system. As shown one ot the electrodes in each unit is connected to the neutral wire of the power system, and the other electrodes are respectively connected to two dierent phase lines oi the power system. Nevertheless, only u single control relay 66 is required and it may be connected in series with either one of the latter two electrodes.

Referring to FlG. l2, there is shown a multiple-unit generator which comprises three separate ones of the units i0 connected in parallel in the steam line so as to provide approximately three times the steam output of thc single unit 10 shown in FlG. 2.

The electrical connections for energizing the electrode 126 are not shown in FlG. i2 but it will be understood that the electrodes in the three units 10 are respectively energized from the three different phases of a three-phase power system and that only a single control circuit is employed and this is operatively connected to one of the units lil in the same manner as it would be connected to a single operating unit 1t)y in a single unit system.

in order to insure that the water from the inlet valve 6G is equally supplied to the generating chambers in each of the units 1), an equalization manifold 121 is connected that water is drained or? in equal quantities from each of the units 10, an equalization manifold 121 is connected between each of the units and a connecting T 122 which is interposed between the inlet valve 65 and the outlet valve 75. 1t will be understood that the valves 65 and 7S may be the solenoid operated valves iwhose controlled circuits are described hereinbefore in connection with FIGS. 8 and 9.

As shown, the equalization manifold 121 includes a single inlet or passageway 123 and a plurality of passageways 124, 1.25 and 126 respectively connected to the thrce chambers of the generating units 10. A battle 127 is centrally located in the manifold 121 so that when the valve 65 is open there is an equal flow of water into each of the separating chambers. To this end it will be observed that the passageways 129 and 130 in the manifold are disposed closer to the passageways 124 and `126 than to the central aperture 12S. The reason for this is that the passageway 125 is fed from both of the passageways 129 and 130 and unless the passageways 129 and 130 are farther from the passageway 125 than from the passageways 124 and 126, an excess amount of water will llow into the central chamber.

In order to equalize the operation of the three separate units 10, an equalization manifold 135 is connected bctween the Separate outlets of the separating units and an outlet conduit 136 to which the pressure operated switch 70 (not Shown in FIG. l2) is connected. The manifold 135 also includes a baille 137 so disposed that the steam pressure in the conduit 136 is equally controlled by each of the generating units 1t). Since control of the generator is affected by the flow of steam out of the generating units 10 and into the conduit 136, as contrasted to the control of the generating units 1t) by the flow of water through the manifold 121 and into the chambers, the passageways 138 and 139 in the steam equalization manifold 135 are positioned closer to the central generating unit than they are to the outside units.

It has been found preferable to mount the separating units 10 in aligned position, as shown in FIG. 12, and under such circumstances the manifolds 121 and 135 should be designed to compensate for the equalization problems described above.

It will be understood, however, that where other arrangements of the units are employed, the equalization problem may be solved in other manners. For example, the three generators 10 could be arranged in an equilateral triangle and fed water through an annular manifold with steam being extracted through an annular manifold. Irrespective of the particular manner in which the generators are mounted, however, unless particular effort is made to equalize both the supply of water to the generators and the extraction of steam therefrom, oscillation with the consequent substantial loss in operating etliciency will result.

While particular embodiments of the invention have been shown, it will be understood, of course, that it is not desired that the invention be limited thereto since modifications may be made, and it is, therefore, contemplated by the appended claims to cover any such moditications as fall within the true spirit and scope of the invention.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A steam generator comprising a vaporizing chamber having a vapor outlet passage extending therefrom for the transfer of vapor to a load, a plurality of electric terminal members extending into said chamber, a domeshaped insulating plate having a cup-shaped recess on the side thereof remote from said outlet passage, said plate being mounted in said chamber on said terminals, said plate being arranged over and in spaced relation to said outlet passage and extending over substantially all of the cross-section of said chamber a plurality of electrodes disposed in said chamber and tixedly mounted on said plate on the side thereof remote from said outlet passage, and conductive means connecting said electrodes to said terminals.

2. A steam generator comprising a housing having an open mouth, an insulating member sealed to said housing over said mouth to define with said housing a pressurizable chamber, a steam outlet opening into said chamber for extracting steam therefrom, a plurality of rigid terminal members secured to said insulating member and extending therethrough into said chamber, and a second insulating member mounted in said chamber on said terminal members in a manner permitting a limited amount of relative movement between said second insulating member and said terminals, said second insulating member being arranged over and in spaced relation to said steam outlet opening, a plurality of electrodes electrically connected to said terminals and rigidly secured to said second insulating member on the side thereof remote from said outlet whereby said second insulating member is interposed between said outlet and said electrodes, said second insulating member being substantially imperforate to provide a barrier between said electrodes and said vapor outlet.

3. A steam generator comprising a housing defining a vaporizing chamber having a drain port at the bottom and an open mouth at the top, a cover member formed of an electrical insulating material, said cover member being sealed to said housing over said mouth, said cover having a centrally disposed steam outlet passageway connected between said chamber and the outside of said cover, a plurality of rigid terminal members secured to said cover and extending therethrough into said chamber, an insulating plate mounted in said chamber on said terminal members, 'said plate having a depending annular ange about the periphery thereof, a plurality of carbon electrodes, each having an arcuate groove at the top thereof for reception of a portion of said depending flange, means for tightly securing said electrodes to said plate with said ange received in said grooves, and means for electrically connecting each of said electrodes to a respective one of said terminals.

4. The invention defined in claim 3 wherein said plate is displaced from said cover and is imperforate and has a plurality of recesses in the periphery thereof providing passageways for vapor from the space between said electrodes to said outlet.

5. The invention defined in claim 4 wherein said housing is generally cylindrical, said plate and electrode assembly is also cylindrical, and the internal diameter of said housing is slightly greater than the external diameter of said assembly whereby substantially all of the vapor generated in said chamber flows through the peripheral passages in said plate.

6. A steam generator comprising a vaporizing cham- `ber having a vapor outlet passage extending therefrom for the transfer of vapor to a load, a plurality of electric terminal members extending into said chamber, an insulating plate arranged adjacent to and over said outlet passage, said insulating plate being spaced from said outlet passage and `being concave on the side thereof remote from said outlet passage, said insulating plate having an aperture to permit the passage of steam from said chamber to said outlet passage, said aperture being remote from said outlet passage, a plurality of spaced electrodes and mounted on said plate on the side thereof remote from said outlet passage, said plate completely overlying the space between said electrodes, and conductive means connecting said electrodes to said terminals.

7. The invention defined in claim 6, wherein said insulating plate has a peripheral rim extending outwardly from said plate on the same side as said recess, said rim surrounding said recess and defining therewith a vapor confining space, and said electrodes are each provided with an arcuate groove for reception of said rim, whereby said electrodes are accurately positioned with respect to said plate.

8. A steam generator comprising a vaporizing chamber having `a vapor outlet passage extending therefrom for the transfer of vapor to `a load, a plurality of electric terminal members extending into said chamber, a domeshaped insulating plate mounted in said chamber on said terminals, said dome-shaped plate separating said Vaporizing chamber into a vaporizing portion and an outlet portion, said vapor outlet passage being centrally located in said outlet portion, said plate having a plurality of peripherally spaced apertures to permit vapor to pass from said vaporizing portion to said outlet portion of the vaporized chamber at positions remote from said vapor outlet passage, a plurality of electrodes disposed in said chamber and xedly mounted on said plate, and conductive means connecting said electrodes to said terminals.

9. The invention defined in claim 2 including a spring for resiliently urging said second insulating member and said terminals into predetermined relative positions.

10. The invention defined in claim 2 including a plurality of exible braided electrical connectors, said connectors being connected `between said electrodes and said terminals.

References Cited in the tile of this patent UNITED STATES PATENTS Re. 24,283 Watson Feb. 26, 1957 905,597 Smyser Dec. 1, 1908 1,462,350 Merrill et al July 17, 1923 1,526,014 Russell et al Feb. 10, 1925 1,663,558 Lawner Mar. 27, 1928 1,665,793 Sandborgh Apr. 1, 1928 1,742,406 M'ascarini Jan. 7, 1930 1,902,842 Eaton Mar. 28, 1933 2,000,628 White May 7, 1935 2,387,156 Katzman Oct. 16, 1945 2,447,294 Vickery Aug. 17, 1948 2,755,372 Fisher et al June 17, 1956 Kasuga Apr. 30, 1957 

3. A STEAM GENERATOR COMPRISING A HOUSING DEFINING A VAPORIZING CHAMBER HAVING A DRAIN PORT AT THE BOTTOM AND AN OPEN MOUTH AT THE TOP, A COVER MEMBER FORMED OF AN ELECTRICAL INSULATING MATERIAL, SAID COVER MEMBER BEING SEALED TO SAID HOUSING OVER SAID MOUTH, SAID COVER HAVING A CENTRALLY DISPOSED STEAM OUTLET PASSAGEWAY CONNECTED BETWEEN SAID CHAMBER AND THE OUTSIDE OF SAID COVER, A PLURALITY OF RIGID TERMINAL MEMBERS SECURED TO SAID COVER AND EXTENDING THERETHROUGH INTO SAID CHAMBER, AN INSULATING PLATE MOUNTED IN SAID CHAMBER ON SAID TERMINAL MEMBERS, SAID PLATE HAVING A DEPENDING ANNULAR FLANGE ABOUT THE PERIPHERY THEREOF, A PLURALITY OF CARBON ELECTRODES, EACH HAVING AN ARCUATE GROOVE AT THE TOP THEREOF FOR RECEPTION OF A PORTION OF SAID DEPENDING FLANGE, MEANS FOR TIGHTLY SECURING SAID ELECTRODES TO SAID PLATE WITH SAID FLANGE RECEIVED IN SAID GROOVES, AND MEANS FOR ELECTRICALLY CONNECTING EACH OF SAID ELECTRODES TO A RESPECTIVE ONE OF SAID TERMINALS. 